Improved packing for pistons and valves



"tluited ltatte pour non.

ULLIAM M. STEVENSON AND AUSTIN PEARCE, OF HARMONY, PENNSYLVANIA, ASSIGNO'RS TO THEMSELVES AND GEORGE E. HANDY, OFy BOSTON, MASSA- OHUSETTS.

Letters Patent No. 96,993, dated November 1G, 1869.

The Schedule referred to in these Letters Patent and making part of the same.

To all persons to n'llomthese presents Imay come:

Be it known. that we, WlLLIAM M. STEvENsoN, of Newcastle, of the county of' Lawrence, and AUSTIN IEARCE, ot' Harmony, of the county of Butler, and State of Pennsylvania, have invented a new and useful Improvement in Engine-Pistons and Valves; and we do hereby declare the same to be fully described iu the following specification, and represented in the accompanying drawings, in which- Y Figure 1 is a side elevation,

Figure 2, a transverse section of a steam-enginev piston as provided with our invention.

Figure 3 is a representation of the interior of the piston, with its cap-plate as removed from it.- The improvement has reference to such pistons as have met-allie ring packings and It consists mainly in each of the packing-rings being constructed with an annular groove, and provided `with au auxiliary packing-ring arranged within such groove, and provided with passages, by which the steam, when the piston may be in operation, will be led into the annular groove, so as to force the large ring against its sea-t, and the smaller against the cap- 'plate next to it.

In the drawings- Y A denotes a piston-rod, having a cylindrical head, B, from the middle of whose periphery an annular rib or flange, a, extends. This rib or flange continues entirely around the head. Its opposite plane faces constitute bearings or seats for two rings, C O', which loosely encompass the piston-head, and are arranged thereon in manner as represented in the drawing..

Each of these rings is kept iu place by one ot' two disks or -ap-plates, 1) D', which lie against the opposite ends of the head B, aud have diameters correspondingto that ot' the flange a disposed midway between them.

Each ot' these rings, ou the side thereof which is next to the next adjacen't cap-plate, is channelled or grooved entirely around it, as shown at I), and there is arranged in such groove an auxlliary ring, c, of lne-tal or other suitable materiali Furthermore, from'the inner circumference of each main ring, C or C', one or more holes, d, are bored into the auxiliary ring-groove.

One or more holes, f, are also bored through the next adjacent cap-plate l) or D". so as to open com munication with the narrow space c or e between the ring and the head B.

When the piston is in operation in a. steam-engine cylinder, the steam will-pass'through the holesf into space c or c', thence through the holes (l iutothe groove of the main ring, and will force the auxiliary ring against the next cap-plate, and the main ringl up to the seat thereof' of the flange, thereby securing close joints 'at the sides ot' the main rino'. Both the main and auxiliary rings are to be split or cut through, so as to enable them to be expanded by the steam, in order that the outer circumference of the main ring maybe forced out into close contact with the boreI of the cylinder.

By our improvement we are enabled to insure close joints at the sides as well as at the periphery of each of the main expansive rings.

Furthermore, by our invention there will be friction I broughton each main ring, to prevent it from being too quickly expanded against the cylinder, the same serving to prevent much wear of the ring and cylinder, which otherwise would he liable to take place.

Our invcntiol-i is equally applicable to various pistous which have their expansive metallic pacliings in other shapes than that ot' a rnfj'. It is also applicable, in some instances, to slide-valves.

Such are diieren-t modes in which we have contemplated the application of that principle or character, by which our invention may be distinguished from others.

Vire therefore claim the arrangement of' the auxiliary ring c and its chamber or groove b, with each or either of the main rugs O C', and with 'passages (lf, lbrleadiug the steam to the inner periphery of the ma-in ring, and thence into the groove b of' such main ting, the whole being substantially as and to operate as hereinbefore explained.

WM. M. STEVENSON. AUSTIN PEAROE.

Witnesses:

R. H. EDDY, S. N. PIPER. 

